Shared tcb structures are made independent

For clone, file descriptor and vm area structures need to be
separate from the tcb and reached via a pointer so that they
can be shared among multiple tcbs.

tasks/mm0/include/vm_area.h

@@ -243,6 +243,11 @@ int validate_task_range(struct tcb *t, unsigned long start,
 /* Changes all shadows and their ptes to read-only */
 int vm_freeze_shadows(struct tcb *task);
 
+static inline void task_add_vma(struct tcb *task, struct vm_area *vma)
+{
+	list_add(&vma->list, &task->vm_area_head->list);
+}
+
 /* Main page fault entry point */
 int page_fault_handler(l4id_t tid, fault_kdata_t *fkdata);